Naked and Not: Two Species of Mole Rats Run Complex Societies Underground

Milius, Susan, Science News

On his first trip into Namibia, Chris Faulkes woke up in his tent with a peculiar kink in his back. The ground beneath him had been flat enough when he went to sleep. Yet the next morning, "there was a whopping great lump," he says. A mound of dirt had arisen under Faulkes. He'd inadvertently found--or been found by--Damaraland mole rats, the very creatures he'd come to study. With one of the oddest social systems yet found in mammals, these sub-Saharan rodents spend their lives in networks of underground tunnels that they continually excavate.

These mole rats and a better-known species called naked mole rats survive in land that goes months without rain. When rain finally comes, the animals go into a frenzy of digging to expand their tunnels before the ground bakes again.

With the mole rats' extreme social system, individuals labor for the sake of the colony. Since the early 1980s, mole rats have been used as models of social organization.

The wrinkled, hairless rodent known as the naked mole rat has achieved celebrity status even outside science. In Faulkes' office at Queen Mary College of the University of London stands a cardboard cutout of the Disney-cartoon character of the naked mole rat Rufus. Even the Wall Street Journal has run a page-one story on naked mole rat charms. The subhead read: "What Is Whiskered and Ugly and Has Little Squinty Eyes?--No, Not Your Former Spouse...."

The Damaraland mole rat that woke Faulkes doesn't have a popular following, but it offers a valuable comparison with the naked mole rats' social behavior. Although the Damaraland's basic biology resembles the naked mole rat's, its social structure has some twists. What's more, recent research has revealed a cast that includes couch potatoes.

Says Nigel Bennett, one of Faulkes' colleagues on the Namibia expedition, "I hope people will realize the haired mole rats are just as interesting as the naked ones, if not more so."

GOOD OLD DAYS No scientist knew much about the biology of mole rats in the 1960s, when Jennifer Jarvis of the University of Cape Town in South Africa began studying the evasive, underground rodents. The family she studied contains several dozen species in sub-Saharan Africa that are neither moles nor rats, but are more closely related to guinea pigs and porcupines.

To find mole rats, a researcher looks for hills of dirt and guesses where to dig to strike a tunnel. When the shovel slices through a passageway, researchers fit it with a tube trap rigged so that a door will snap down and capture any mole rat that ventures inside.

Many times, the mole rats detect the breach, says Jarvis. In those instances, instead of trotting into the trap, the mole rats wall off the violated tunnel. That means even more digging for the scientists, often in 40[degrees]C heat and full sun.

Jarvis collects captured mole rats aboveground in tubs until she's retrieved a whole colony. To protect the captives from temperature swings, Jarvis shades the tubs during the day and tucks the animals in at night with carpet backing and hot-water bottles.

When Jarvis first brought a colony of naked mole rats back to her lab, she struggled to find suitable burrows. First, she filled a glass-sided box with soil. "They dug a marvelous burrow system" she says. "The next day, they dug again--and it collapsed." Now, she knows that soil soft enough for easy digging is a rare stimulus for mole rats to embark on urban renewal. "The colony goes crazy," she says.

So, she made her lab colony a plaster of paris home riddled with tunnels that wouldn't collapse. Soon though, the mole rats "looked like tiny white ghosts with beady eyes," she says. Finally, she settled on mole rat runs custom-built from plastic tubing.

Bringing the animals into the lab provided other challenges, which Jarvis would later recognize as clues for one of her major research contributions. …

The rest of this article is only available to active members of Questia

Print this page

While we understand printed pages are helpful to our users, this limitation is necessary
to help protect our publishers' copyrighted material and prevent its unlawful distribution.
We are sorry for any inconvenience.